German patent specification 43 26 016 discloses an automotive vehicle, preferably a golf caddy, which comprises a high-frequency position finder and an ultrasonic position finder. When the golf caddy has determined the direction of the hand-held transmitter by way of high-frequency position finding, it will approach the transmitter on a straight path at a relatively high speed until it reaches an ultrasonic position finding range in which ultrasonic position finding and reduced speed are automatically switched to. Upon reaching a predetermined minimum distance from the golf player, the golf caddy will stop.
The prior-art golf caddy has already proved to be a success in practice. A disadvantage of the combined high-frequency and ultrasonic position finding system is, however, that the golf caddy does not exactly follow the path which has been predetermined by the golf player with the hand-held transmitter, but approaches the path polygonally, which may be disadvantageous, depending on the condition of the path. The automotive vehicle would not be able to follow a mobile transmitting device along a small winding path, but could only approach such a path laterally, depending on the course of the track. Moreover, the prior-art system does not offer the possibility of banning specific parts of the ground for the automotive vehicle, since it would, for example, move into a pond if the hand-held transmitter was at the other side of the pond and gave the signal "follow".
JP-Abstract 3-134715 A discloses a golf caddy which is equipped with a satellite-controlled positioning system (global positioning system GPS) for determining the exact position. The GPS serves to make visible the position of different golf caddies on a display in a central office.
JP-Abstract 5-046079A also discloses a golf caddy with GPS which serves to store the distance traveled by a golf caddy in a memory using a periodic timer and to display the respective positions of, and the distances covered by, the golf caddy on a display by means of position coordinates of the golf course which are stored on a CD ROM.
U.S. Pat. No. 5,331,561 discloses a system wherein a vehicle without driver follows a lead vehicle at a short predetermined distance on a road. Both vehicles are equipped with a GPS receiver. Using lateral sensors, the lead vehicle gathers side range data which are given by the respective distance between the vehicle and lateral objects. Moreover, the distances which have so far been covered are measured with respect to the respective side range data. The lead vehicle transmits these data to the follower vehicle which also determines such side range profiles and compares these data with the transmitted data. If there are deviations, the course of the follower vehicle will be corrected such that the side range data agree again.
U.S. Pat. No. 5,043,903 discloses a system for supporting the flying movements of helicopters or aircrafts which are flying in a formation. The document is concerned with positioning each aircraft within such a formation and with maintaining the mutual distances between the aircraft.
It is the object of the present invention to provide a guide system for an automotive vehicle which ensures exact guidance. Moreover, a method for exactly guiding a vehicle is to be indicated. Moreover, an improved method for controlling the vehicle is to be indicated.
These objects are achieved according to the invention by the features indicated in patent claims 1 and 9.
Advantageous developments of the invention are characterized in the subclaims.